Occultist

An occultist is one who studies the supernatural, be it as a matter of personal interest or a dedicated study, often in a setting where magic is not in everyday use. Some occultists may derive spellcasting power from their studies; others simply amass knowledge of the supernatural.

Alternatively, occultist is a character class in the 3rd edition Masque of the Red Death-setting, and the 1st edition of the Pathfinder-setting.